Pump



P. A. LEE

April 5, 1966 PUMP 4 Sheets-Sheet 1 Filed Jan. 15, 1965 IN VENTOR BY 5M. T M -7 ATToRNE1/s P. A. LEE

April 5, 1966 PUMP 4 Sheets-Sheet 2 Filed Jan. 15, 1965 INVENTOR Pa A455,

ATTORNEYS April 5, 1966 P. A. LEE 3,244,110

PUMP

Filed Jan. 15, 1965 4 Sheets-Sheet 5 pauz. fl. 455,

INVENTORS BY 6%, M M y A kw ATTORNEYS P. A. LEE

April 5, 1966 PUMP 4 Sheets-sheaf. 4

Filed Jan. 15, 1965 INVENTORS ATTORNEYS United States Patent 3,244,110PUMP Paul A. Lee, Chicago, IlL, assignoito The Planet ProdnetsCorporation, (Ihicago, I ll., a corporation of Illinois Filed Ian. 15,1965. Ser. No. 427,212 11 Claims. (Cl. 103-126) aligning the shafts sothatthey will operate in parallel with each'other. Of course, ifsufficient time, skill and effort are spend in machining and assemblingthe pump, the gear shafts can be mounted substantially in parallel, butthe'time and effort necessary to construct such a pump is expensive.toprovide an inexpensive gear pump in which the gear shafts are locatedsufficiently parallel to permit the pump to operate efiiciently at highpressures.

Furthermore, the bearings and gears of fluid pumps are subject to wearand periodically must be replaced. Attempts have been made to prolongthe life of the bearings and the gears with some success, but when thebearings finally become worn,-the pumps must be substantially rebuilt.

Attempts-have beenmade to produce lightweight, reliable gear pumps inwhich the gears and other components are formed of plastic. The plasticgears in the pumps are resistant to corrosion and, therefore, thesepumps are particularly well suited for the pumping of food products orother liquids which may corrode a conventional pump. A lightweight,efficient plastic pump, however, must be sufficiently rugged towithstand the high internal fluid pressure, and the torque and vibrationthan-smitted to the pump from an electric motor.

Accordingly, it is an object of this invention to improve the alignmentof the mounting of gear pump shafts ,and to maintain these insubstantial alignment.

It is a further object of this invention to provide a construction inwhich wear and strain of the gear mountings is minimized. It is anotherobject of this invention to provide a gear pump which is capable ofpumping athigh pressures, and yet, is inexpensive to manufacture andeconomical to maintain.

These objects are accomplished in accordance with a preferred embodimentof the invention in which the drive gear of the pump is secured to adrive shaft and the idler gear is mounted on an idler shaft. The gearshave substantially the same width. The idler shaft and drive shaft aremounted in end plates on opposite sides of the gears. The end plates areidentical in size and shape and the holes for the shafts are line reamedthrough both end plates simultaneously so that they are in alignment.Bearing inserts are mounted in the shaft holes in the end plates tosupport the shafts for rotation. Replaceable liner plates are interposedbetween the end plates and the gears to form wear surfaces. The housingof the pump is formed to accommodate the outer configuration of the endplates. The side walls of the housing enclose the gears and end platesassembled within the housing and the most critical dimensions, themountings for the gear shafts, are fixed by the end plates.

This preferred embodiment of the invention is illustrated in theaccompanying drawings in which:

FIG. 1 is a perspective view of a pump embodying this invention;

Consequently, it has not been possible 3,244,119 Patented Apr. 5, 1966FIG. 2 is an exploded view in perspective of the gear mountingarrangement;

FIG. 3 is a cross-sectional view of the pump along the line 3-3 in FIG.4;

FIG. 4 is a cross-sectional view of the pump along the line 4-4 in FIG.3;

FIG. 5 is a cross-sectional view of a modified form of the pump alongthe line 5-5 in FIG. 8;

FIG. 6 is a cross-sectional view of a portion of the modified form ofthe pump along the line 6-6 in FIG. 8;

FIG. 7 is a detail elevational view of a portion of the end cover of themodified form of the pump;

FIG. 8 is an elevational view of the valve end of the modified pump;

FIG. 9 is a detail sectional view along the line 9-9 in FIG. 5 showingan end plate and a portion of the housing of the modified pump;

- FIG. 10 is a top plan view of the sub-base; and -FIG. 11 is across-sectional view of the sub-base along the line 11-11 in FIG. 10.

The gear pump shown as an embodiment of this invention, includes ahousing 2 through which is provided an inlet opening 4 and an outletopening 6. Transverse conduits 8 and 10 extend through the housingintersecting the inlet opening 4 and outlet opening 6, respectively, todistribute fluid within the housing. The base of the housing is providedwith a conventional pad 12 for supporting the housing in an uprightposition. Two bores 14 and 16 extend through the housing. The bores aresubstantially parallel and in vertical alignment, and the centerdistance between the axes of the bores is approximately the centerdistance of the gears of the pump.

A drive gear 18 is secured to a drive shaft 20, which is preferablymetal, by any suitable means, such as molding the gear 18 on the shaft20 or by adhesively bonding the gear to the shaft. An idler gear 22 issecured to an idler shaft 24 and the size of the gears is such that whenin mesh, they fit closely within the gear bores '14 and 16 respectively.The gear shafts are journaled in end plates 26 and 23. Each end plate isformed in a single piece and both of the end plates are substantiallyidentical. Shaft holes 36 and 32 in which the gear shafts 20 and 24 aremounted are formed in both end plates in the same operation to insurethat the shaft holes of each pair of holes are parallel with those ofthe other pair, and the holes of each pair have the same diameter andlocation. Bearing inserts 34 and 36 may be fitted, if desired or needed,in the shaft holes 30 and 32, respectively, as shown in FIG. 2. Theidentical bearing end plates 26 and 28 are mounted on opposite sides ofthe gears 18 and 20 to support the shafts 20 and 24. To preventexcessive wear between the gears and the end plates, liners 38 and 40 ofsubstantially the same configuration as the end plates may be interposedbetween the end plates and the gears.

The opposite ends of the housing 2 are enclosed by end walls 42 and 44.A metal cover plate 46 is mounted between the housing 2 and the end wall42. A plurality of sealing rings 47 prevent the leakage of fluid alongthe cover plate 46. The cover plate 46 is provided with openings whichregisterwith the conduits 8 and 10 to provide communication between theinterior of the pump and a bypass conduit 48. An adjustable springloaded valve 49 controls the flow of fluid through the bypass conduit48. The end walls 42 and 44 are secured to the housing by bolts 50 whichextend through the end walls 42 and 44, cover plate 46 and housing 2.

A boss 52 is provided on the end wall 44, and the drive shaft 20 extendsthrough a bore in the boss. Conventional V-belt pulleys 56 are mountedon the drive shaft 20 and keyed to the shaft so that the pulleys 56 turnwith the shaft 20.

Important features of this invention are that the pump is light inweight, efiicient exen at high pressures, and yet inexpensive tomanufacture, and that it requires a minimum of maintenance. The optimumbenefits of this invention are obtained if unstressed parts are moldedof a light weight thermoplastic and by use of thermoplastic to mold thepump parts, no drilling of the end plate bearings is required. Thethermoplastic resin should have good dimensional stability and becapable of being molded to close tolerances. One thermoplastic resinwhich has been found particularly suitable is Delrin acetal resin whichis available commercially from E. I. .du Pont de Nemours and Company.

The parts of the pump which are preferably molded of thermoplasticresins are the housing 2, end walls 42 and 44, end plates 26 and 28,drive gear 18, idler gear 22, and pulleys 56. The parts which arepreferably made of metal are the drive shaft 20, idler shaft 24, coverplate 46, bearing inserts 34 and 36, bolts 50 and the liners 38 and 40.

Any type of suitable bearing material may be used in the bearinginserts, including mica, sinter-ed bronze impregnated with oil, or steelbacked bearings coated with Teflon. For simplicity of manufacture andassembly, the pump is symmetrical about its vertical and horizontalaxes, except for the end walls, the conduits 8 and 10, the the driveshaft and the pad on the housing. The use of end plates 26 and 28 whichare substantially identical is an important feature of the invention forobtaining close tolerances at a minimum of cost. These end platesprovide increased efficiency, especially in high pressure and increasedalignment, thereby eliminating possible friction and wear whch resultsin less maintenance problems and increase life use. The outer edges ofthe end plates fit within the horizontal bores of the housing 2. The endplates 26 and 28 are molded on the same die and, therefore, havethe samedimensions within a close tolerance.

This assures that corresponding holes in the opposite end plates willhave the same diameter and will be located at the same position in theend plates. The end plates provide the sole support for the drive shaftand the idler shaft and, since they are symmetrical and substantiallyidentical, the shafts are parallel and the proper center distance whenmounted between the end plates. This construction permits a highpressure pump to be manufactured without the high costs of precisionjigs and fixtures usually found necessary to achieve the accuratemounting of the shafts.

Interchangeable bearing mountings, as are provided by the removable endplates, permit various sizes of gears to be used with each size of pumphousing. The end plates may be made of different thicknesses to fill thespace between the gears and the end walls thereby causing more or lessquantity of liquid pumped, effecting a saving in tool costs for sizesadjacent thereto. Furthermore, various types of bearings may be insertedin the shaft holes of the end plates according to the anticipatedoperating conditions of the pump.

Another important feature of the invention is that if wear occurs, thepump may be easily disassembled and the worn parts may be replacedeasily. Liners 38 and 40 are removable as are the bearing inserts 34 and36. This pump is therefore inexpensive to maintain, light in weight andlow in initial cost, and yet, is capable of pumping fluid at highpressure.

A modified form of the pump of this invention is illustrated in FIGS. to11. As shown in FIG. 5, the modified form of the pump has a housing 60which is substantially the same as that of the pump shown in FIGS. 1, 3and 4. Within the housing 60, a drive gear is molded on a round driveshaft 64. The drive shaft 64 is preferably formed of metal and has aflat or splines formed in the shaft at the location where the drive gear62 is molded on the shaft 64 to prevent the gear from turning relativeto the shaft. The drive shaft 64 is journaled for rotation in bearinginserts 66, which are supported in the housing 60 by end plates 68 and70 on opposite sides of the gear 62. An idler gear 72 is molded on anidler shaft 74-, which also has a flat or splines formed in the shaftfor preventing rotation of the gear relative to the shaft. The idlershaft 74 is journaled for rotation in bearing inserts 76 which aremounted in the end plates 68 and 70, and the idler shaft '74 is spacedfrom the drive shaft 64 an appropriate distance for the gears 62 and 72to be in mesh.

The bearing inserts 66 and 76 are substantially longer than thethickness of the end plates 68 and 70 in which they are mounted, therebyproviding a large bearing surface for journaling the respective shafts64 and 74. The end plates 58 and 70 correspond to the end plates 26 and28, as shown in FIGS. 3 and 4, and have substantially the same shape asthe intersecting bores in the housing 60 for accurately positioning thegears in the proper relation to each other. The use of single end platesextending between the drive shaft and idler shaft on opposite sides ofthe gears reduces the end play of the gears. In order to preventexcessive wear or galling of the surfaces of the end plates 68 and 70,thin metal liners 78 and 80 are provided between the gears and the endplates.

High pressure fluid which leaks outwardly along the shafts 64 and 74urges the end plates 68 and 70 toward the gears 62 and 72. Although theliners 78 and 80 protect the end plates from excessive wear, the lateralforce on the gears causes their opposite faces to become worn andincreases the power required to drive the gears 62 and 72. Accordingly,the end plates 68 and 70 each have a shoulder 81 extending around theedge of each end plate, as shown in FIG. 5. The shoulders 81 fit incorresponding grooves in the housing 6% and prevent displacement of theend plates toward the gears 62 and 72.

A cover 82 closes one end of the housng 60 and has a sleeve 84 extendingoutwardly therefrom. A plurality of sealing rings 86 are mounted in acylindrical recess 88 in the sleeve 84 to prevent the leakage of fluidalong the drive shaft. The rings 86, which may be formed of rubber or aplastic having a low coefficient of friction, are retained in the recess88 by a spider 90. The drive shaft 64 is journaled in a needle bearingassembly 92 in the sleeve 84 and a seal 94 is mounted in the end of thesleeve adjacent the bearing 92. A carbon hearing may be substituted forthe needle bearing assembly 92. When a viscous fluid is being pumped,any seepage would tend to impose a drag on the needle bearings, but willhave no negative effect on the carbon bearing. Therefore the carbonbearing is preferred when a viscous fluid is being pumped.

The pump may be driven by an electric motor. Power is transmitted fromthe motor to the pump by a belt extending between pulleys on the pumpand the motor. For this purpose, a V-belt pulley 96 is secured on thedrive shaft 64. The pulley has a ball bearing assembly 98 mountedtherein. The inner race of the bearing assembly is pressed on the sleeve84, which supports the pulley 96 for rotation, so that the belt grooveis substantially in the same plane as the bearing assembly 92 and thedrive shaft 64 is not bent or distorted by tension in the drive belt.The pulley 96 is secured on the drive shaft 64 in a suitable manner, asby a snap ring 99 and a key 100 which is inserted in a keyway in theshaft and cooperates with a keyway in the pulley 96. The shaft 64extends beyond the pulley, as shown in FIG. 5, so that the shaft 64 maybe directly coupled to another shaft, if desired.

As the pulley rotates, air circulation is induced through axiallyextending holes 191 in the pulley for cooling the bearing assembly 98.These holes 101 are spaced about the axis of the pulley in number andsize suflicient for adequate ventilation and air circulation. Theyshould extend substantially from the space between the bearing races.Furthermore, since the pulley is mounted on the sleeve 84, rather thandirectly on the shaft 64, the heat from the belt friction is nottransferred from the pulley to the shaft 64.

At the opposite end of the housing 60, a cover 102 is secured overtheend of the housing. A gasket 104, preferably formed of metal, isinterposed between the cover 162 and the housing 66. The cover 102 hasbosses 106 formed thereon and cylindrical recesses 108 are provided inthe bosses in the cover 102 for receiving the ends of the drive shaft 64and the idler shaft 74, and their corresponding bearing inserts 66 and76. A plurality of ribs 110 provide additional support for the bosses166. A similar boss 112 is provided on the opposite cover 82 forreceiving the opposite end of the idler shaft 74 and the bearing insert76 in a cylindrical recess 114 in the boss 112. 1

In high pressure pumps, it is necessary to provide a bypass for thefluid to prevent excessive pressure from building up within the pump. Asshown in FIG. 8, the pump has an inlet opening 116 and an outlet opening118, correspondingto the inlet opening 4 and the outlet opening 6 of thepump shown in FIG. 3. The openings 116 and 118 extend into the interiorof the housing 61! for supplying fluid to the gears 62 and 72 and forconducting the high pressure fluid out of the housing, respectively. Atransverse bore 120 in the pump housing 60 communicates between theoutlet opening 118 and the gasket 104, as shown in FIG. 6. The gasket104 has a hole 122 which is in alignment with the bore 12%, and acylindrical projection 124 formed on the cover has a central bore 125 inaxial alignment with the hole 122. A plurality of longitudinal ribs 126in the bore 125 form a cage for a ball 128 forming a valve. The diameterof the ball 128 is slightly larger than the diameter of the hole 122 andthe hole forms a seat against which the ball is yieldably urged by aspring 132.

The end of the spring 130 is retained in a socket formed in a stud 132.The cylindrical projection 124 has internal threads which cooperate withexternal threads on the stud 132 and by turning the stud relative to thecylindrical projection, the force of the spring on the ball 128 may beadjusted. A hexagonal socket 134 is provided in the stud 132 to receivea wrench for turning the stud relative to the cylindrical projection124. A cap 136 has internal threads which also cooperate with externalthreads on the stud 132, and a washer 138 is compressed between the capand the projection when the cap is tightened against the end of thecylindrical projection 124. The stress on the threads of the stud 132due to the compression of the washer 138 prevents the stud from turning,although the pump is vibrating severely. After the tension in the spring130 has been adjusted, the stud 132 should remain in its adjustedposition, but if the wrench socket 134 is exposed, it is an invitationfor someone to insert a wrench in the socket and turn the stud 132. Thecap 136, therefore, is provided to enclose the stud 132 and to shieldit.

As shown in FIG. 8, a passageway 140 is formed in a rib 142 in the cover102. The passageway 140 extends between the bore of the cylindricalprojection 124 and a transverse bore in a projection 141 on the cover102, which transverse bore in the projection 141 registers with atransverse bore 144 in the housing 60 which in turn communicates withthe inlet opening 116. Consequently, if the fluid pressure in the outletside of the pump is sufliciently high to displace the ball 128 from itsseat in the hole 122, fluid is bypassed to the low pressure, intake sideof the pump through the bore 120, the passageway 140 and the bore 144.The pressure at which fluid begins to bypass may be adjusted by turningthe stud 132 to vary the tension of the spring 130 on the ball 128.

Since the fluid pressure in the pump may cause leakage of fluid from thegears 62 and 72 outwardly through their respective bearing inserts 66and 76, the cylindrical recesses in the bosses 106 and 112 aresubstantially larger than the diameter of the bearing inserts and arespaced away from the ends of the bearing inserts and the shafts to allowleakage fluid to accumulate in the cylindrical recesses in the covers.There is suflicient space between the inserts and their respectivecylindrical recesses to allow for expansion of the fluid in therecesses. The fluid pressure at the outlet of the pump is greater thanthe fluid pressure at the inlet of the pump when the pump is inoperation and this pressure difference maybe utilized to return theleakage fluid to the ,inlet side of the pump. Each of the end plates 68and 70 has a transverse groove 146, as shown in FIGS. 5 and 9, in theside opposite the gears 62 and 72. The groove extends from the center ofthe end plate to the low pressure side of the end plate, so that leakagefluid can flow between the end plate 68-or 7t) and the housing 60 andinto the inlet opening adjacent the gears. The flow of leakage fluidalso cools the bearings and the shafts. This is the point of lowestpressure in the ump, and accordingly, and leakage of fluid through theends ofthe bearing inserts will flow through the grooves 146 and back tothe inlet side of the pump, thereby preventing fluid from leaking out ofthe housing 60. The shoulders 81 prevent the end plates from beingdisplaced toward the sides of the gears by the high pressure of thefluid at the outer ends of the bearing inserts.

As shown in FIGS. 5 and 7, right-angular ribs 148 extend outwardly fromthecover 82 adjacent to each bolt hole 150, which extends through thecovers and the housing. The ridges 148 are spaced from the bolt holes150 sufficiently to embrace the head of'a bolt 152 which extends throughthe bolt hole 150 and clamps the covers 82 and 102 to the housing 60.The ribs 148 adjacent each bolt hole 150 prevent the head of the boltfrom turning while a nut 154 is being threaded on the bolt.

In order to provide better stability for the pump housing 60, thehousing base 155 may-be mounted on a sub-base 156, as shown in FIGS. 5,8, l0 and 11. The sub-base 156 has right angular ribs 158, which arespaced a distance corresponding to the length and width of the base 155of the housing 60, so that the base of the housing may be supportedbetween the ribs 153. Bolt holes 160 are provided in opposite ends ofthe sub-base 156 in alignment with corresponding holes in the base 155of the housing 66, for clamping the housing against the sub-base 156.One of the bolt holes may be in the form of a slot to compensate forinaccurate spacing of the holes in the housing. Bolt holes 162 are alsoprovided in the-outer ends of the sub-base for securing the sub-base toa motor platform or other support.

In operation, the pump of this invention is mounted adjacent an electricmotor and a drive belt extends between the motor pulley and the pulley96 for rotating the drive shaft 64. A fluid inlet line is connected tothe inlet opening 116 and an outlet line is connected to the outletopening 118. The bypass valve is adjusted by turning the stud 132 untilthe spring force on the ball 128 is suflicient to maintain the ballagainst its seat at lower pressures, but the ball is displaced away fromthe hole 122 at the desired outlet fluid pressure. The cap 136 is thenreplaced on the projection 124 for locking the stud 132 againstrotation. When the motor turns the pulley 96, the gears 62 and 72 arerotated and fluid flows through the pump in paths from the inlet side ofthe pump between the gear teeth and the housing 60 to the outlet side ofthe pump. The region between the gears on the inlet side of the pump isat a low fluid pressure, while the area between the gears on the outletside of the pump is at a relatively high fiuid pressure when the pump isin operation.

While this invention has been illustrated and described in certainembodiments, it is recognized that variations and changes may be madetherein without departing from the invention as set forth in the claims.

I claim:

1. A gear pump comprising a housing, fluid inlet and outlet openings onopposite sides of the housing, parallel bores through the housing, adrive gear in one of the bores, an idler gear in the other bore in meshwith the drive gear, said drive gear being secured on a drive shaft, anend wall secured to the housing over the bores, said drive shaftextending through the end wall, said end wall having a sleeve extendingoutwardly therefrom in surrounding relation to said shaft, a pulleyhaving a belt groove therein, first bearing means mounting the pulleyfor rotation on said sleeve, said belt groove being in substantially thesame plane as said bearing means, second bearing means between saidsleeve and said shaft, said second bearing means being in substantiallythe same plane as said first bearing means and said belt groove, andmeans for connecting said pulley to said drive shaft.

2. A gear pump according to claim 1 wherein said sleeve includes acylindrical recess coaxial with said shaft and said second bearing meansbeing mounted in said recess, and fluid sealing means on opposite sidesof said second bearing means.

3. A gear pump according to claim 2 wherein said second bearing means isa needle bearing assembly and said pulley has openings extending axiallytherethrough for cooling said first bearing means.

4. A gear pump comprising a housing, fluid inlet and outlet openings onopposite sides of the housing, parallel bores through the housing, adrive gear in one of the bores, an idler gear in the other bore in meshwith the drive gear, said drive gear being secured on a drive shaft,said idler gear being mounted on an idler shaft, end plates in thebores, each of said end plates having a uniform thickness and planaropposite faces and being in one integral piece and extending between andencircling the drive shaft and the idler shaft, bearing inserts in saidend plates in position for journaling said drive shaft and said idlershaft, said bearing inserts having a greater length than the thicknessof said end plates, and a cover secured to said housing over said bores,said cover having cylindrical recesses therein in position to receivesaid bearing inserts and said drive shaft and idler shaft, saidrecessesbeing spaced radially from the respective inserts and shafts forreceiving leakage fluid therebetween.

5. A gear pump according to claim 4 wherein said end plates each haveradial shoulders thereon in position for engaging said housing and saidrecesses individually enclose said inserts and shafts.

6. A gear pu-mp comprising a housing, fluid inlet and outlet openings onopposite sides of the housing, parallel bores through the housing, adrive gear in one of the bores, an idler gear in the other bore in meshwith the drive gear, said drive gear being secured on a drive shaft,said idler gear being mounted on an idler shaft, end plates in thebores, each of said end plates having planar opposite faces and being inone integral piece and extending between and encircling the drive shaftand the idler shaft, said end plates having grooves therein on the sideopposite said gears, said grooves extending from between said idlershaft and drive shaft to the edge of the end plate adjacent the fluidinlet opening, whereby fluid adjacent the outer side of each end plateis maintained under relatively low pressure.

7. A gear pump according to claim 6 wherein said grooves are formed insaid end plate faces on the side opposite said gears, each of saidgrooves being substantially straight and extending perpendicular to aline in the plane of each face and interconnecting the central axes ofsaid gears.

8. A gear pump comprising a housing, fluid inlet and outlet openings onopposite sides of the housing, parallel bores through the housing, adrive gear in one of the bores,

an idler gear in the other bore in mesh with the drive gear, said drivegear being secured on a drive shaft, said idler gear being mounted on anidler shaft, end plates in the bores, each of said end plates havingplanar opposite faces and being in one integral piece and extendingbetween and encircling the drive shaft and the idler shaft, a coverextending over said intersecting bores, said housing having a pair oftransverse passageways communicating independently with said cover, oneof said passageways extending from said inlet to said cover and theother passageway extending from said outlet to said cover, said coverhaving a conduit therein communicating between said transversepassageways, value means in said conduit, said valve means tending toopen in response to a fluid pressure differential between the pressureof the fluid in said outlet opening and the fluid in the inlet opening,a coil spring in said cover in position for yieldably urging said valvemeans closed, a stud engaging one end of said spring and being threadedin said cover and a cap threaded on the stud on the end opposite thespring, whereby the stud adjusts the spring force and the cap engagesthe cover and locks the stud in its adjusted position.

9. A gear pump according to claim 8 wherein said stud has a hollowrecess in one end for receiving said coil spring and a wrench socket inthe opposite end.

10. A gear pump comprising a housing, a fluid inlet and outlet openingson opposite sides of the housing, parallel bores through the housing, adrive gear in one of the bores, an idler gear in the other bore in meshwith the drive gear, said drive gear being secured on a drive shaft,said housing having a base integral therewith for supporting the housingin an upright position, a platform, and means for fastening the base tothe platform, said platform having upstanding ribs extending along saidbase, whereby the platform rigidly supports the base while the pump isin operation.

11. A gear pump comprising a housing, fluid inlet and outlet openings onopposite sides of the housing, parallel bores through the housing, adrive gear in one of the bores, an idler gear in the other bore in meshwith the drive gear, said drive gear being secured on a drive shaft, acover on each opposite end of the housing extending over theintersecting bores, and bolts extending through said covers and saidhousing for clamping the covers to the housing, said bolts having headswith at least one flat side, one of said covers having ridges extendingalong the flat side of the heads of said bolts, whereby the bolts areprevented from turning while a nut is being tightened on the oppositeend of each bolt.

References Cited by the Examiner UNITED STATES PATENTS 2,682,836 7/1954Orr 103-126 2,714,856 8/1955 Kane 103-126 2,728,301 12/1955 Lindberg103-126 2,772,638 12/1956 Nagely 103-126 2,823,616 2/1958 Toyoda 103-1262,880,676 4/1959 Succop 103-126 2,986,097 5/1961 Chrzanowski 103-1262,996,998 8/1961 Gold et al 103-126 3,057,302 10/1962 Lockett 103-1263,077,840 2/1963 Wood -1 103-126 3,113,524 12/1963 Fulton 103-1263,128,710 4/1964 Blomgren et al 103-126 MARK NEWMAN, Primary Examiner.

WILBUR J. GOODLIN, Examiner,

1. A GEAR PUMP COMPRISING A HOUSING, FLUID INLET AND OUTLET OPENINGS ONOPPOSITE SIDES OF THE HOUSING, PARALLEL BORES THROUGH THE HOUSING, ADRIVE GEAR IN ONE OF THE BORES, AN IDLER GEAR IN THE OTHER BORE IN MESHWITH THE DRIVE GEAR, SAID DRIVE GEAR BEING SECURED ON A DRIVE SHAFT, ANEND WALL SECURED TO THE HOUSING OVER THE BORES, SAID DRIVE SHAFTEXTENDING THROUGH THE END WALL, SAID END WALL HAVING A SLEEVE EXTENDINGOUTWARDLY THEREFROM IN SURROUNDING RELATION TO SAID SHAFT, A PULLEYHAVING A BELT GROOVE THEREIN, FIRST BEARING MEANS MOUNTING THE PULLEYFOR ROTATION ON SAID SLEEVE, SAID BELT GROOVE BEING IN SUBSTANTIALLY THESAME PLANE AS SAID BEARNG MEANS, SECOND BEARING MEANS BETWEEN SAIDSLEEVE AND SAID SHAFT, SAID SECOND BEARING MEANS BEING IN SUBSTANTIALLYTHE SAME PLANE AS SAID FIRST BEARING MEANS AND SAID BELT GROOVE, ANDMEANS FOR CONNECTING SAID PULLEY TO SAID DRIVE SHAFT.